http://tags.library.upenn.edu/tag/data+ncdb PennTags Feed for /tag/data+ncdb PennTags Feed http://tags.library.upenn.edu/makerecord/voyager/8140 http://tags.library.upenn.edu/makerecord/voyager/8140 CensusCD neighborhood change database (NCDB) [electronic resource] : 1970-2000 tract data : selected variables for US Census tracts for 1970, 1980, 1990, 2000 and mapping too / Geolytics. http://tags.library.upenn.edu/makerecord/voyager/452 http://tags.library.upenn.edu/makerecord/voyager/452 CensusCD neighborhood change database (NCDB) [electronic resource] : 1970-2000 tract data : selected variables for US Census tracts for 1970, 1980, 1990, 2000 and mapping too / Geolytics.